The present invention relates to an implant, in particular a bone replacement implant for insertion into a bone cavity formed by resection, for example, or an intervertebral implant for insertion between two adjacent vertebral bodies of a human or animal spine, which can be brought from a normal position, in which the implant encompasses a maximum total volume, into an insertion position, in which the implant encompasses an insertion volume, which is smaller than the maximum total volume.
For treatment of a disc prolapse, the affected intervertebral disc is usually partially or completely removed and the section of the spine formed by the two vertebrae adjacent to the damaged disc reinforced. To achieve such a reinforcement, the two vertebral bodies of the adjacent vertebrae are usually fused by means of a spacer, also referred to as a “cage”. The spacer is inserted between the two vertebral bodies, wherein a spacer is usually selected that has a height corresponding to the original height of the intervertebral disc. The spacer is preferably not solid, so that bone substance can grow into the spacer.
The disadvantage with such implants has proved to be their size, i.e. they cannot typically be inserted in a minimally invasive manner.
In addition, inserted balloons are known in particular in vertebroplasty, which are inserted into a bone cavity and can be filled with bone cement. The disadvantage with such implants is that they are not at all suitable as intervertebral implants, since such a balloon implant always expands in the direction of least resistance, particularly upon filling with a fluid.
Therefore, it is an object of the present invention to improve an implant of the above-described type such that the implant can be inserted through as small as possible an opening in a human or animal body and nevertheless have a high inherent stability.